Definir la herramienta HAND para Profundidad y Extensión de Inundación (Arc Hydro)

kat_h

Hola, <\/P>

Estoy intentando delimitar una llanura de inundación de un pequeño arroyo en ArcGIS Pro 2.9 con Arc Hydro. <\/P>

He estado siguiendo el flujo de trabajo presentado en el reciente seminario web: Arc Hydro: Inundaciones y Pronósticos.<\/P>

1. Rellenar sumideros en el DEM basado en LiDAR
2. Dirección del flujo y Acumulación del flujo
3. Distancia de flujo para crear un ráster HAND 
4. Herramienta ArcHydro: Definir Profundidad y Extensión de Inundación basada en HAND<\/P>

¿Cómo se determina cuál debe ser el parámetro 'Profundidad de Inundación de Entrada'?
El seminario web menciona que es el umbral vertical, pero no estoy seguro de qué significa eso. ¿Es la profundidad máxima del arroyo?<\/P>

Sólo tengo datos LiDAR, el DEM y la línea/raster del arroyo disponibles. <\/P>

Cualquier consejo sobre esta herramienta es apreciado, ¡gracias! <\/P>

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DeanDjokic

When using HAND method for "flooding", the "Input Flood Depth" is the depth above stream centerline that you want to "flood" with. 

What that specific value is, is up to you.  For example, if you use the "max depth of the creek", that is the equivalent of the "bankfull" and most of the resulting flood polygon should be contained within the channel.  Anything higher should start spilling into the overbanks and you should get "flooding".

So where do you get that number?  Depends on what you are doing.  It can come from the observations (e.g. high water mark or a stage from a gage) or through flow modeling and rating curve to convert flow to depth.  If you are doing the rating curve approach, make sure that the rating curve is based on the same resolution data you used to derive HAND with (or is adjusted accordingly).

And remember that inherent assumption in HAND flood modeling approach is that your water surface is uniform (constant) and parallel to the bottom of the channel.  For each channel segment.  So if you expect that the depth will change (significantly) as you go downstream, you should partition the overall stream into multiple segments that have uniform (but variable from segment to segment) depth and then use "Define HAND-based Flood Depth and Extent from Table" tool to get the floodplain.  More work but might give you better results.

If you stream segment is short, then first follow the approach you have presented (single reach), see if you like the results, and if not, then use the "table" approach.  Note that you will have to reprocess the input data and partition the streams and get their catchments before you can use the "table" approach.

Hope this helps.